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Shao et al. 1999
Shao, X.M., Rhodes, C.T. and Holden, D.N. (1999). RF radiation observations of positive cloud-to-ground flashes. Journal of Geophysical Research 104: doi: 10.1029/1999JD900036. issn: 0148-0227.

During the summers of 1995 and 1996 we conducted broadband HF-UHF and narrowband VHF radio frequency (RF) observations of positive cloud-to-ground (+CG) flashes at Langmuir and Los Alamos laboratories, New Mexico. These observations indicate that positive leaders to ground produce no or very weak radiation from HF to UHF. The broadband system was able to record 2 ms data each time it was triggered. For a +CG the system was usually triggered by the return stroke, and a 1 ms pretrigger period was coincident with the positive leader process. It was commonly observed that no or little radiation was associated with the leader process in the 1 ms pretrigger period. The narrowband VHF system employed a logarithmic power amplifier and recorded one 1 s data each time it was triggered. The narrowband observations show that strong and often continuous radiation occurs at the beginning of the +CGs, but the radiation usually becomes intermittent and impulsive during the last few tens of milliseconds preceding the return strokes. The observations for most of the +CGs also show complete lack of radiation a few ms before the beginning of the return strokes, suggesting that the ongoing downward positive leaders were quiet at VHF, at least during the final few ms. The results of this study for natural positive leaders are in agreement with the results obtained from laboratory gap discharges and rocket-triggered lightning. ¿ 1999 American Geophysical Union

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Keywords
Meteorology and Atmospheric Dynamics, Lightning, Meteorology and Atmospheric Dynamics, Atmospheric electricity, Meteorology and Atmospheric Dynamics, Instruments and techniques, Atmospheric Composition and Structure, Constituent sources and sinks
Journal
Journal of Geophysical Research
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Publisher
American Geophysical Union
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